1. Technical Field
The present invention relates to valves. More specifically, this invention relates to an automatic shut-off valve which is responsive to the flow of fluid through the valve when such flow is low.
2. Background Information
Unintentional or accidental discharges are a well known problem with all pressurized fluid distribution systems. Today""s consumers who make use of water delivery systems for both domestic and industrial purposes are well aware of the problems of forgotten faucets, broken pipes, property damage and the resultant high water bills.
One means for solving such problems is by automatically interrupting flow at the source after a predetermined volume of flow has occurred. Various techniques are available for providing such interruption, each with their own advantages and disadvantages. For example, an electronic flow meter may be placed in the line whereby a signal is sent to a totalizing computer, which in turn sends a signal to an electric valve in the flow line interrupting flow. While such a solution may be satisfactory for industrial use, it is cost-prohibitive for domestic purposes. Another example involves placing a turbine or nutating disk in the flow line whereby flow is converted into rotary motion, driving a clockwork mechanism that closes a valve after a certain number of revolutions. A third example for interrupting flow is a valve having a plug that is forced against a seat by fluid flow. The seating of the plug is delayed by a dashpot movement retarder, thereby allowing a volume of liquid to pass before seating and stopping flow.
While the first two methods work, the expense of the first and the reliability of the second limit their widespread usage. The third technique is widely known in the art. Many different methods of providing a metered flow into or out of the dashpot are taught. An issue that must be addressed with such a method or valve is reset, i.e., emptying and refilling the dashpot and unseating the plug in preparation for another cycle.
In metering dashpot flow, two conditions are neededxe2x80x94(1) a predicable and constant pressure gradient related to the flow through the valve, and (2) a flow path restrictor in series communicating this pressure gradient to the dashpot, thereby slowing flow and producing a desired time delay effect. In resetting the mechanism, it is common to use a spring that is gradually compressed as timing progresses, providing stored energy to effect reset when called for. The problem with this technique is that as the spring compresses it exerts more and more force, thereby impeding the movement of the timing mechanism, which itself is moved by the constant pressure gradient. Accordingly, there is a need for a valve that provides for an immediate compression of the spring when flow begins so that movement of the cup shaped plug is unaffected.
Further, the dashpot type valve is generally designed for the low end of a predetermined range of flow. In that low volume of flow, it is difficult for the dashpot type valve to provide the minimum pressure gradient necessary for operation. Accordingly, there is a need for a valve wherein the device used to compress the spring also forms a pressure regulator thereby guaranteeing the proper pressure gradient, even at very low flow rates.
The present invention disclosed herein alleviates the drawbacks described above with respect to responding to fluid flow through a valve, particularly low fluid flow. The valve of the present invention is easily installed in a flow line. It allows the control of the flow of the volume of liquid to be unattended. The range of flow through the valve is wide, ranging from a nominal trickle to full flow.
The valve of the present invention is in one embodiment an automatic reset valve for controlling a volume of flow. The valve has a timing cup for effecting turnoff of flow through the valve; a piston able to be lifted by the flow of the fluid thereby allowing the fluid to flow through the valve; and a regulator in communication with the piston and having one or more ports through which flow from an inlet of the valve is able to flow through to an outlet of the valve.
As designed, the valve of the present invention is easily and conveniently installed in a flow line. Its simple design allows it to be inexpensively manufactured. It may be manufactured in a wide range of sizes, based upon the size of the flow line to be served. By proper selection of materials, the present invention may be used for controlling a wide variety of flow.
The invention permits the unattended control of the volume of flow there through. By controlling the volume of flow, water waste and flood damage from forgotten or broken lines are minimized or even eliminated. The valve of the present invention provides for an automatic reset should the flow volume during one event not exceed its predetermined limit. Likewise, the valve of the present invention provides for an automatic reset once pressure is equalized after a turnoff event, such as turning off the flow supply or a fixture valve.
The valve of the present invention is comprised of at least two components that enable it to overcome those limitations that are encountered with typical dashpot type valves. These components include a timing cup for containing a predetermined, preferred volume of fluid, and a regulator integral with the valve, rather than separate from it yet in communication with it, for controlling the total volume of flow through the valve.
As disclosed herein, the timing cup provides a preferred means of containing a variable volume of fluid. Other means that would likewise serve the same function include a bellows or a diaphragm. Such containers contain a predetermined volume of fluid based upon its stroke length and diameter required for movement of the container to occur at a constant pressure. The container further provides a means of effecting turnoff of flow through the valve.
The regulator provides a stable fixed base that other components of the valve react against. It has one or more ports that provide communication between the inlet and outlet for fluid flow. By covering these ports, flow through the valve is effectively turned off.
The general beneficial effects described above apply generally to each of the exemplary descriptions and characterizations of the devices and mechanisms disclosed herein. The specific structures through which these benefits are delivered will be described in detail herein below.